The subject invention relates to envelopes, and specifically, to envelopes for containing circular meter charts which are typically used by utilities, oil companies and the like. The charts in questions are essentially circular graphs upon which conditions such as pressure, temperature, etc. are monitored as they change with time. In operation, the chart slowly revolves in accordance with the passage of time, and any changes in the conditions being monitored are precisely recorded by a writing instrument onto the chart. It will be appreciated that the charts contain precisely located graph lines and reference characters associated with particular lines. Thus, it is very important that the charts be kept completely flat and uncreased during transportation such that the data recorded thereon reflects the accurate state of the conditions monitored.
Typically, charts are shipped in envelopes which can generally contain on the order of up to fifty charts. With so many charts in an envelope, there is a tendency for the charts to slip relative to one another with portions of some charts becoming creased or damaged during handling. One known means of minimizing slippage of the charts is to use envelopes which are square in configuration. There is a significant shortcoming, however, associated with the use of square envelopes. Specifically, the automatic processing equipment typically used by the U.S. Post Offices, while being able to process rectangular envelopes, cannot properly process square envelopes. Thus, square envelopes must be processed by hand. As the Post Offices move more and more to automatic equipment, there is an increasing possibility that square envelopes will no longer be accepted for mailing.
Accordingly, it is an object of the subject invention to provide a rectangular, but non-square, envelope for containing circular meter charts, the envelope including means for preventing slippage of the charts contained therein.
It is another object of the subject invention to provide an envelope having the above characteristics which is simple in construction and relatively inexpensive to manufacture.